level2

Assignment name  : last_word
Expected files   : last_word.c
Allowed functions: write
--------------------------------------------------------------------------------

Write a program that takes a string and displays its last word followed by a \n.

A word is a section of string delimited by spaces/tabs or by the start/end of
the string.

If the number of parameters is not 1, or there are no words, display a newline.

Example:

$> ./last_word "FOR PONIES" | cat -e
PONIES$
$> ./last_word "this        ...       is sparta, then again, maybe    not" | cat -e
not$
$> ./last_word "   " | cat -e
$
$> ./last_word "a" "b" | cat -e
$
$> ./last_word "  lorem,ipsum  " | cat -e
lorem,ipsum$
$>

-------------------------------------------------------------------------------

void	last_word(char *str)
{
	int i = 0;

	while (str[i] != '\0')
		++i;
	while (i >= 0 && (str[i] == ' ' || str[i] == '\t' || str[i] == '\0'))
		--i;
	while (i >= 0 && str[i] != ' ' && str[i] != '\t')
		--i;
	++i;
	while (str[i] != '\0' && str[i] != ' ' && str[i] != '\t')
	{
		write(1, str + i, 1);
		++i;
	}
}

int		main(int argc, char **argv)
{
	if (argc == 2)
		last_word(argv[1]);

	write(1, "\n", 1);
	return (0);
}

Assignment name  : reverse_bits
Expected files   : reverse_bits.c
Allowed functions:
--------------------------------------------------------------------------------

Write a function that takes a byte, reverses it, bit by bit (like the
example) and returns the result.

Your function must be declared as follows:

unsigned char	reverse_bits(unsigned char octet);

Example:

  1 byte
_____________
 0100  0001
     ||
     \/
 1000  0010

------------------------------------------------------------------------------

unsigned char	reverse_bits(unsigned char octet)
{
	unsigned char out = 0;

	out = out | ((octet & 128) >> 7);
	out = out | ((octet & 64) >> 5);
	out = out | ((octet & 32) >> 3);
	out = out | ((octet & 16) >> 1);
	out = out | ((octet & 8) << 1);
	out = out | ((octet & 4) << 3);
	out = out | ((octet & 2) << 5);
	out = out | ((octet & 1) << 7);
	return (out);
}

Assignment name  : do_op
Expected files   : *.c, *.h
Allowed functions: atoi, printf, write
--------------------------------------------------------------------------------

Write a program that takes three strings:
- The first and the third one are representations of base-10 signed integers
  that fit in an int.
- The second one is an arithmetic operator chosen from: + - * / %

The program must display the result of the requested arithmetic operation,
followed by a newline. If the number of parameters is not 3, the program
just displays a newline.

You can assume the string have no mistakes or extraneous characters. Negative
numbers, in input or output, will have one and only one leading '-'. The
result of the operation fits in an int.

Examples:

$> ./do_op "123" "*" 456 | cat -e
56088$
$> ./do_op "9828" "/" 234 | cat -e
42$
$> ./do_op "1" "+" "-43" | cat -e
-42$
$> ./do_op | cat -e
$
-------------------------------------------------------------------------------

#include <stdio.h>
#include <stdlib.h>

int	main(int argc, char **argv)
{
	if (argc == 4)
	{
		int a = atoi(argv[1]);
		int b = atoi(argv[3]);
		char operator = *argv[2];

		if (operator == '+')
			printf("%d", a + b);
		else if (operator == '-')
			printf("%d", a - b);
		else if (operator == '*')
			printf("%d", a * b);
		else if (b == 0)
			printf("UNDEFINED");
		else if (operator == '/')
			printf("%d", a / b);
		else if (operator == '%')
			printf("%d", a % b);
	}
	printf("\n");
	return (0);
}

Assignment name  : camel_to_snake
Expected files   : camel_to_snake.c
Allowed functions: malloc, free, realloc, write
--------------------------------------------------------------------------------

Write a program that takes a single string in lowerCamelCase format
and converts it into a string in snake_case format.

A lowerCamelCase string is a string where each word begins with a capital letter
except for the first one.

A snake_case string is a string where each word is in lower case, separated by
an underscore "_".

Examples:
$>./camel_to_snake "hereIsACamelCaseWord"
here_is_a_camel_case_word
$>./camel_to_snake "helloWorld" | cat -e
hello_world$
$>./camel_to_snake | cat -e
$

#include <unistd.h>

void	camel_to_snake(char *str)
{
	while (*str != '\0')
	{
		if (*str >= 'A' && *str <= 'Z')
		{
			write(1, "_", 1);
			*str = *str + ('a' - 'A');
		}
		write(1, str, 1);
		++str;
	}
}

int		main(int argc, char **argv)
{
	if (argc == 2)
		camel_to_snake(argv[1]);

	write(1, "\n", 1);
	return (0);
}

Assignment name  : alpha_mirror
Expected files   : alpha_mirror.c
Allowed functions: write
--------------------------------------------------------------------------------

Write a program called alpha_mirror that takes a string and displays this string
after replacing each alphabetical character by the opposite alphabetical
character, followed by a newline.

'a' becomes 'z', 'Z' becomes 'A'
'd' becomes 'w', 'M' becomes 'N'

and so on.

Case is not changed.

If the number of arguments is not 1, display only a newline.

Examples:

$>./alpha_mirror "abc"
zyx
$>./alpha_mirror "My horse is Amazing." | cat -e
Nb slihv rh Znzarmt.$
$>./alpha_mirror | cat -e
$
$>

#include <unistd.h>

void	alpha_mirror(char *str)
{
	while (*str != '\0')
	{
		if (*str >= 'A' && *str <= 'M')
			*str = 'Z' - (*str - 'A');
		else if (*str >= 'a' && *str <= 'm')
			*str = 'z' - (*str - 'a');
		else if (*str >= 'N' && *str <= 'Z')
			*str = 'A' + ('Z' - *str);
		else if (*str >= 'n' && *str <= 'z')
			*str = 'a' + ('z' - *str);

		write(1, str, 1);
		++str;
	}
}

int		main(int argc, char **argv)
{
	if (argc == 2)
		alpha_mirror(argv[1]);

	write(1, "\n", 1);
	return (0);
}